Schuette said Thursday that anything short of physically separating the Great Lakes and Mississippi River watersheds leaves the lakes region's environment and economy at risk. The plan released by the administration this week promises improvements to barriers and further work on technologies such as underwater cannons.

It promises a report with options for a permanent solution later this year.

Michigan is among five states suing the federal government to seal off the Great Lakes basin. A federal judge rejected the suit in December, but the states have appealed.